Hydraulic brake system



Aprll 6, 1954 w. R. BRAUN, SR I 2,674,352

f HYDRAULIC BRAKE SYSTEM Filed Feb. 7, 1951 `2 Sheets-Sheet.' l

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April 6, 1954 Filed Feb. 7, 1951 W. R. BRAUN, SR

HYDRAULIC BRAKE SYSTEM 2 Sheets-Sheet 2 9/ f4, gf 47 Patented Apr. 6,1954 UNITED STATES PATENT OFFICE HYDRAULIC BRAKE SYSTEM William R..Braun, Sr., NorthArlington; N i J. Application' February `7, 1951;SerialNo: 2095845" (Cl. 188--152.)v

Claims.` l

This-invention relates to iiuid-'pressurebraking systems for motorvehicles,

A prime object of the present-inventionrisi-to provide fav brakingsystem for a motor vvehicle wherein each wheel has afbra'key and avfluid pres-l sure actuatedmotor` or piston and cylinder deviceassociated therewith. for actuating thecorresponding. brake, incombination with twoy fluidA pressure producing systems each forsupplying luidepressure to all of saidfluid pressureactuated motors and4a check cylinderand valve` connected between each.J iiuidpressurevactuated. motor. and thespipes fromboth .of'. said fluid .pressure sys.-tems, so that one of said fluid pressure systems normally. actuatesgthe.service brakesof vthe vehicle and the. other .fluidpressuresystem actu?ates said-.brakesin .the event of 4failure oftherst-.mentionedsystem.dueto leakage or break.- age therein,` andthecheck. cylinder` and. valve prevents;.v the ow of iiuid from eitherof said.

uid pressure systems into the other during operation of the brakes.-

Another. cbj ect of the .invention is the provision in a hydraulicbraking,V system employing ltwo separate iiuid pressure systems, onezofwhich is for emergency purposes, of novel means by which asi-ngiemanually actuated operatingmember when moved. in .one directionoperates. one system to eiect the setting of all. of the brakes of thevehicle, but in case of said brakes failing to operateeectively throughsaid system, the operating member willby` continued movement in the samedirection eiectthel applicationV of the emergency system for operatingthe brakes.

Another object of the invention is to provide a novelbraking systemwhich is simple in construction, highly efficient inoperation,.re1atively cheap to make and install, has relatively fewparts and is strong and not likely to. get out of. order.

Broadly, the invention consists in the provision of'a braking systemhaving two master cylinders, each of which operates .thefour brakes of'the vehicle. One cylinder controls the flow of id through' the normalline to the brakes andthe other cylinder, however, controls the ow of'uid to the brakes through an emergency line. The pistons of therespective master cylinders are operated-by a single foot pedal.

Thev inventionwill be better understood from thedescription thereof tolfollow taken ink con...

nection with the accompanying drawings in whiche- Figurel is a'plan'View' of a hydraulic braking systemembodying 'myinvention as applied-tolanv automobilefportions ofi whichare shown:4

Figure 2 is Yan` enlarged y vertical sectional view.

ofl-the-master cylinders and associatedparts, the parts1being shown ininoperative position.

Figur-e3 is a similar view but showing the parts movedr to a positionf`preparatory to emergency operation 4of the system.

Figurel 4 is anenlarged fragmentary part elevational and partdiagrammatic View showing the master cylinderv structure connected to a;

wheel cylinder, the latter beingshownin section.

Figure?) is aV vertical sectional view takenV on= the-'plane ofthe line5-5of Figure 2.\

Referring .to thev drawings indetail, thebrakingi system-includes anelongated reservoir. I divided.l by` a partition. wall 21 into two.compartments 34 and@ Compartment 4 is formed with anllingopening E.Whichtmayrbeclosed by a .removalcap Communication between.. the twocompart-l mentsv is-Y provided by'an opening 'I through .the

partitionwall 2;

A main master cylinder 3 is formed underneath.

thecompartment 3 anda similar auxiliary master cylinder; 9;.- shorterin'` length, is formed under.-

neatli` thecompartmentmaa partition .wall Ill' separatingthe.two.rcylinders, each cylinder come prisingza part'of.l oneof twofluid pressure systems.

Ther-cylinder.. 8.;.is..formed witha lling .port l l and .a:compensating '.port il 2, both. leading .to the compartment. aand; witha. dischargeport I3.;

An. integral screw-threaded.tubular extension I4.

outeriopen end. of the lcylinderzand havingan.

aXiaLopeningZS. The 4skirt portion. 2l is formed with-.anelongatedtapered central recess. 24 for the .receptionof one. end orathrustor push rod 25..extending through. the axialopening 23 in'the plugmember. A gasket 26 seals the junction between the. outer-.end of theplug and the. rod. The plug member may be provided witha port 21 for.the escapeof Huid.

Thepush rod 25`is pivotally connectedto a foot pedal lever 28' asindicated at 29,the pedallever'being pivotedon` a suitable support 3l):A conventional retractilespring -3l connects the pedal lever to a fixedsupport 32 on the chassis 33. Thus it will be seen that by thisconnection between the pedal lever and the piston the piston will bemoved when the pedal is actuated.

The skirt portion 2| of the piston tapers inwardly from its outer endtowards the head portion thereby providing in conjunction with the wallof the cylinder an annular chamber 34 at the rear of the head portionand this chamber is in constant communication with the compartment 3 ofthe reservoir through the lling port H.

The head portion 25 of the piston carries a packing cup 35 and when thepiston is in its retracted position this packing cup uncovers thecompensating port I2 for permitting free communication in bothdirections between the cylinder S and the compartment 3.v The forwardface of the piston head 2) is formed with an integral, elongatedextension rod 36 which normally extends through an opening 31 in thepartition wall I0 and into the cylinder 3. A spiral spring 38 encirclesthe extension rod 36 and has one end seated in the packing cup 35 andits other end in a packing cup 39 positioned against the wall iii. Thespring normally holds the piston against forward compressive motion andthe cups against displacement and also assists in returning the pistonto its retracted position.

The auxiliary master cylinder 9 has an open outer end closed by a plugor head member 40 having a tubular extension 4i. The plug member isformed with an axial opening forming a discharge port 42 which leads tothe opening in the plug extension. A cup-shaped member 43 is mounted inthe recess and has a central opening 44 in its base for slidablysupporting a springpressed valve member 45. A coupling 46 threaded on tothe plug extension provides a connection between the discharge port 42and a fluid pressure delivery pipe 41.

A dependent compression piston reciprocates in the cylinder Si and isconstructed similarly to the piston in cylinder 8 having a head portion48 and a skirt portion 59, the latter having an elongated recess 59. Apacking cup 5i is fastened to the face of the head portion by a screw52. The cup provides a seat for a spiral spring 53, the other end of thespring seating against the inner face of the plug member 4d. The skirtportion of the piston is tapered and reduced in cross section to providein conjunction with the wall of the cylinder 9 an annular chamber 54communicating by way of a, filling port in the cylinder wall with thecompartment 4 of the reservoir. Ports 55 in the skirt portion of thepiston provide free communication between the recess 55 and the annularchamber 54 for the passage of the fluid during the retraction stroke ofthe piston.

The delivery pipe I9 connects with a branch pipe 51 leading to the frontof the vehicle and with a branch pipe 58 leading to the rear thereof.Pipe 51 has branches 59 and S0 connected to one end of check cylinders6i and 62, respectively, mounted on the brake drums 63 of the brakes ofthe front wheels 64. Pipe 58 connects with branch pipes 65 and Secommunicating with one end of check cylinders 61 and E8, respectively,mounted on the drums 69 of the brakes of the rear wheels 10.

The delivery pipe 41 connects with a branch pipe 1I leading to the frontof the vehicle and with a branch pipe 12 leading to the rear thereof.Pipe 1l has branches 13 and 14 connected to the 4 other end of thecylinders 6| and 62, respectively. Pipe i2 connects with branch pipes 15and 16 connected to the other end of cylinders 61 and 68, respectively.

rl'he check cylinders 6|, 62, 61 and 68 are similarly constructed and asshown in Figure 4 each comprises a cylindrical tubular body 11 with anintegral extension 18 above the top wall of the body. A threaded annularplug 19 having an axial bore closes one end of the cylinder and asimilar plug B closes the other end. A central discharge port 8l leadsto a central passage 82 in the extension 18. On each side of thedischarge port is a compensating port 83.

A floating compression piston 84 reciprocates in the cylinder and isprevented from displacement therein by the end plugs. The end of one ofthe branch pipes from the normal pipe line IS, for example, pipe BD isconnected to the axial bore in plug 19 and the end of one of the branchpipes from the emergency pipe line 41, for example, pipe 14 is connectedto the axial bore of the other plug 80.

The passage 82 of the extension 18 of each check cylinder opens into anordinary fluid pressure actuated motor or wheel cylinder 81 associatedwith each brake drum so that the fluid forced through said passage underpressure operates the motor which in turn actuates friction elements orshoes of the brake drum of the Wheel. A retractile spring returns thefriction elements when pressure is released. Such a fluid motor or wheelcylinder and associated parts is disclosed in Patent 2,324,031.

in normal operation, when the operator depresses the foot pedal lever 28to apply the brakes, force is transmitted from this lever through therod 25 to the piston in the main master cylinder 8 resulting in movingthe piston on its compression stroke. During the initial movement of thepiston on its compression stroke the packing cup 35 on the head of thepiston closes the compensating port l2 in the cylinder and pressure isimposed 0n the fluid in the cylinder 8 forward of the piston head,resultingin the discharge of fluid from the cylinder through thedischarge port I3, past the unseated valve I1 and through the deliverypipe i9 and its branches to the check cylinders S2, 63, 51 and 68 andfrom said check cylinders through their passages 82 to the fluidpressure motors or wheel cylinders, causing energization of the fluidmotors or wheel cylinders with the resultant spreading of the frictionelements or shoes into braking engagement with the brake drums of thewheels.

rIhe movement of the piston in cylinder 8 is such as to equalizepressures in the various branches leading to the brakes to the end thatthe brakes associated with the wheels may be applied with equal forceand effect.

Upon release of the applied force on the foot pedal lever 2B, the leverreturns to its normal or retracted position under the inuence of theretractile spring 3l. As the foot pedal lever returns to its normalposition, the push rod 25 is retracted, resulting in the release of thepiston in the cylinder 8 whereupon said piston moves to its retractedposition under the iniluence of the spring 38.

If a leak or break occurs in the normal fluid line or system, the fluidwill escape through said leak or break and no braking effect is producedupon depression of the foot pedal lever. According to the presentinvention, however, in such case, the depression of the foot pedal leverwill through the rod 25 move the piston in cylinder 8 forwardly untilits packing cup 35 closes the discharge port I3 in the cylinder. At thesame time, the extension rod 36 is carried forward into the cylinder 9and through the recess 49 in the skirt portion of the piston in saidcylinder and into engagement with the head portion 48 of the piston asshown in Figure 3. When the extension rod is thus in engagement with thehead portion of the piston, compensating ports 85 and 86 formed in theextension rod 36 are positioned in the opening 3l in the partition walllil permitting the ilud from cylinder il to circulate and pass into therecess 50 of the piston skirt portion in cylinder 9 and through ports 56into the chamber 5t in the cylinder to permit movement of the piston 26after it has closed port I3 as shown in Fig. 3. Continued pressure onthe foot pedal lever will cause the extension rod 36 to force the pistonin cylnder il forwardly on its compression stroke against the action ofspring 53. During this compression stroke, the packing cup 5I will closethe compensating port 8l in the wall of cylinder 9v and pressure isimposed on the nuid forward of the piston head 46 resulting in thedischarge of fluid through the discharge port ft2, past the unseatedvalve d5 and through the delivery pipe 41 and its branches to the checkcylinders 6l, 62, 6'! and 68. From the check cylinders the fluid passesto the pressure motors or wheel cylinders of the wheels for operatingthe brakes of the wheels.

When pressure on the foot pedal lever is released, the pistons incylinders 8 and il will be returned to normal retracted position by thesprings 38 and 53, respectively.

Thus it will be seen that I have provided a hydraulic braking systemwhereby fluid is Supplied to the brakes of the four wheels of thevehicle either under normal or emergency conditions thereby ensuringeffective braking under all conditions.

Changes in details of construction might be made without departing fromthe principle of the invention.

What I claim is:

l. A hydraulic braking system for a motor vehicle, comprising brakingdevices for al1 of the wheels of the vehicle, a main master cylinderhaving a pressure producing piston, manual means for actuating saidpiston, an auxiliary master cylinder independent of said main mastercylinder having a pressure producing piston, conduit means for placingthe main master cylinder in communication with all of said brakingdevices, conduit means for placing the auxiliary master cylinder incommunication with all of said braking devices, and a lost motion meansof connection between said pistons whereby upon a failure of the pistonin said main master cylinder to develop fluid pressure. said latterpiston upon traveling a predetermined distance in its compression strokewill initiate movement of the piston in the auxiliary master cylinderfor developing pressure therein which pressure will be transmittedthrough its associate conduit means to the braking devices.

2. A hydraulic braking system for a motor vehicle including brakingdevices for all of the wheels of the vehicle, a main master cylinderhaving a pressure producing piston and having a valve controlleddischarge port, manual means for actuating said piston, an auxiliarymaster cylinder independent of said main master cylinder having apressure producing piston and having a valve controlled port, conduitmeans associated with the discharge port in the main master cylinder forplacing said main cylinder in communication with the braking devices,conduit means associated with the discharge port of the auxiliarycylinder for placing said auxiliary cylinder in communication with thebraking devices, and a lost motion means of connection between saidpistons whereby upon a failure of the piston in said main mastercylinder to develop fluid pressure, said latter piston upon traveling apredetermined distance in its compression stroke will initiate movementof the piston in the auxiliary master cylinder for developing pressuretherein which pressure will be transmitted through its discharge portand associated conduit means to the braking devices.

3. A hydraulic braking system for a motor vehicle including braking`devices for all of the wheels of the vehicle, a main master cylinderhaving a pressure producing piston and having a valve controlleddischarge port, manual means for actuating said piston, an auxiliarymaster cylinder coaxial with but independent of said main mastercylinder' and separated therefrom by a partition wall and having apressure producing piston and a valve controlled port, conduit meansassociated with the discharge port in the main master cylinder forplacing said main master cylinder in communication with the brakingdevices, conduit lneans associated with the discharge port in theauxiliary master cylinder for placing said auxiliary cylinder incommunication with the braking devices, an extension rod formed on thepiston in the main cylinder extending through a hole in said partitionwall, and a skirt portion formed on the piston in the auxiliary mastercylinder opposite said extension rod having a recess disposed in thepath of said extension rod whereby upon travel of the piston in the maincylinder a, pre-determined distance in its compression stroke theextension rod carried thereby will engage the piston in the auxiliarycylinder and move the latter piston for developing pressure in saidauxiliary cylinder, which pressure is transmitted through its valvecontrolled port and associated conduit means to the braking devices.

fl. A hydraulic braking system as denned in claim 3 characterized byspring means for retracting the pistons in the .main and auxiliarycylinders.

5. In a fluid pressure actuating system for applying the brakes to thefour wheels of a motor vehicle, braking devices for all of said wheels,a main master cylinder having a discharge port, conduit means associatedwith said discharge port for placing said main master cylinder incommunication with the braking devices, an auxiliary master cylinderdisposed in alignment with said main master cylinder and forming anextension thereof, a partition wall between said cylinders formed with ahole therethrough, said auxiliary cylinder having a discharge port,conduit means associated with the discharge port of said auxiliarycylinder for placing said auxiliary cylinder in communication with thebraking devices, a piston reciprocable in said main cylinder and havingan extension rod formed thereon extending therefrom through the hole insaid wall in liquid-tight relation to the wall of said hole and into theauxiliary cylinder, manual means for actuating said piston, a pistonreciprocable in said auxiliary cylinder, and a lost motion connectionbetween said extension rod and the4 piston in said auxiliary cylinderwhereby upon the travel of the piston in the main cylinderapredetermined distance in its compression stroke the extension rod willengage the piston in the auxiliary cylinder and move the latterpistonfor developing fluid pressurein said auxiliary cylinder which pressureis transmitted through its discharge port and associated conduit meansto the braking devices.

6. A fluid vpressure actuating system as defined inclaim 5 characterizedby spring means for retracting the pistons in the main and auxiliarymaster cylinders.

7. A hydraulic braking system for a four wheeled vehicle includingbraking devices for all of the wheels, a main master cylinder having afluid pressure producing piston, manual means for actuating said piston,a check cylinder operatively connected to each of said braking devices,pipe lines operatively connecting said main master cylinder with saidcheck cylinders, an auxiliary master cylinder independent of said mainmaster cylinder having a uid pressure producing piston, pipe linesoperatively connecting said auxiliary master cylinder with said checkcylinders, and a lost motion means of connection between said pistonswhereby upon the travel of the piston in the main cylinder apredetermined distance said latter piston will move the piston in theauxiliary cylinder for developing pressure therein which pressure istransmitted through its associated pipe lines to the braking devices.

8. In a hydraulic braking system for a vehicle, the combination withbraking devices for all of the wheels of the vehicle, a reservoir tohold braking fluid for said braking system, a main master cylinderhaving a discharge port and having a compensating port connecting saidmaster cylinder to said reservoir, an auxiliary master cylinder having adischarge port, a piston reciprocable in said main cylinder and adaptedwhen moved in one direction to force fluid under pressure out of saidcylinder through its discharge port, manually operated means for movingsaid piston in said direction, a piston reciprocable in said auxiliarycylinder, a check cylinder connected to each braking device, fluidconducting means connected with the discharge port in said main cylinderand having branches connected to said check cylinders, fluid conductingmeans connected with the discharge port in said auxiliary cylinder andhavngbranchesconnected to said check cylinders, a lost motion means ofconnection between said pistons and means controlled by the piston insaid main cylinder whereby during initial movement of said latterpistonA on its compression stroke said compensating port in the maincylinder is closed and during continued movement of said main piston thepiston in the auxiliary cylinder is connected to said main pistonandactuated to produce fluid pressure in the auxiliary cylinder whichpressure is transmitted through the discharge port in said auxiliarycylinder and its associated duid conducting means to the check cylindersand braking devices.

9. A hydraulic braking system for a vehicle defined in claim 8characterized by spring means for retracting the pistons in both themaster cylinders.

10. A hydraulic brake system for a motor vehicle as defined in claim 1wherein each of said braking devices includes a fluid pressure actuatedmotor and with the addition or a cylinder and piston device for each ofsaid fluid pressure actuated motors, the cylinders of said piston andcylinder devices being connected at one end to the conduit means forsaid master cylinder and at their opposite ends to the conduit means forsaid auxiliary cylinder and With each of the cylinders of said pistonand cylinder` devices having an outlet intermediate its ends connectedto the inlet of the corresponding fluid pressure actuated motor, wherebywhen liuid is flowing from one or" said main or auxiliary mastercylinders said piston of the piston and cylinder device will preventflow of fluid into said conduit of the other main or auxiliary mastercylinder.

References Cited in the le of this patent UNITED STATES PATENTS NumberName Date 1,943,886 Carroll Jan. 16, 1934 1,987,435 Engel Jan. 8, 19352,107,111 Etchison Feb. 1, 1938 2,162,114 Oliver June 13, 1939 2,174,615Bowen et al. Oct. 3, 1939 2,209,343 Masteller June 30, 1940 2,239,751Kritzer Apr. 29, 1941 2,300,694 Overbeke Nov. 3, 1942 2,409,335 VonStackelberg Oct. 15, 1946

